i just bought a new to me 4.0, v-6, automatic, ranger, with 8500 miles. i am going to change oil tomorrow and use synpower 5w30 with a motorcraft filter, from now on out. is this a good choice for a synthetic? it was between that and Mobil 1. it has valvoline conventional in it now that was put in 500 miles ago by the ford dealer. i like and have used Mobil 1, but i also like valvoline. i tow a cargo trailer often, and at my age this will probably be my last vehicle. do you all agree with my choice of oil and what about 5000 mile oil change intervals. it never gets short trip use and about 70% highway.